1. Technical Field
The present invention relates to a metal-insulator-metal (MIM) capacitor and to an associated production method, and in particular to an MIM capacitor suitable for a dual damascene process.
2. Background Information
Capacitors are required in a large number of applications, such as for example, electronic filters, analog-to-digital converters, control circuits and in particular in analog circuits. In semiconductor technology, in which a large number of different functions are integrated on a single chip, so-called metal-insulator-metal (MIM) caps or MIM capacitors are therefore increasingly being used. Such an MIM capacitor is a special type of capacitor in which two metal plates are formed parallel to the surface of a semiconductor wafer and are separated only by a capacitor dielectric.
However, the production of conventional MIM capacitors is very complex, since sometimes up to three lithographic steps are required to produce them. Furthermore, conventional MIM capacitors often have a very high leakage current and an undesirably high extrinsic defect density, which is caused by the influence of the Cu electrodes that are usually used.
US patent publication US 2004/0224474 A1 discloses an MIM capacitor and an associated production method according to the prior art in which a first capacitor electrode is formed in a first intermediate dielectric, subsequently an electrically conducting diffusion barrier layer is selectively formed on the surface of the capacitor electrode, furthermore a second intermediate dielectric is formed and an opening is etched in it to expose a partial region of the diffusion barrier layer. Then, a so-called “high-k” capacitor dielectric is deposited over the entire surface area and first a Cu seed layer and then a Cu filler material on top are introduced on its surface to fill the opening. After a planarizing step, the Cu introduced is closed off by a further diffusion barrier layer, and a further intermediate dielectric can be formed for subsequent interconnect levels.
Although in the case of such an MIM capacitor a greatly reduced leakage current is already obtained along with a reduced extrinsic defect density, the method is cost-intensive and considerable problems arise, in particular for subsequent process steps. In particular, it is not possible in the case of the conventional MIM capacitors for a low-cost dual-damascene process to be carried out to form further interconnects and contacting assemblies without additional process steps.